Share-Based Compensation (Activity Related To Stock Options) (Detail) (USD $)	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011
Number of shares, Outstanding options, Beginning balance	1,097,620	1,301,539
Number of shares, Outstanding options, Granted	217,230	94,196
Number of shares, Outstanding options, Exercised	(44,278)	(188,192)
Number of shares, Outstanding options, Forfeited or expired	(26,164)	(21,867)
Number of shares, Outstanding options, Ending balance	1,244,408	1,185,676
Number of shares, Outstanding exercisable	788,594	856,944
Weighted average exercise price, Outstanding options, Beginning balance	$ 50.14	$ 45.52
Weighted average exercise price, Outstanding options, Granted	$ 51.78	$ 63.09
Weighted average exercise price, Outstanding options, Exercised	$ 29.28	$ 32.44
Weighted average exercise price, Outstanding options, Forfeited or expired	$ 58.17	$ 57.29
Weighted average exercise price, Outstanding options, Ending balance	$ 51.00	$ 48.78
Weighted average exercise price, Outstanding exercisable	$ 49.19	$ 45.83
Weighted average remaining contract life, Outstanding options, Ending period	5 years	4 years 5 months
Weighted average remaining contract life, Outstanding exercisable, Ending period	3 years 2 months	3 years 2 months

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Net number of share options (or share units) granted during the period.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees can acquire the shares reserved for issuance on stock options awarded.

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Weighted average remaining contractual term of exercisable stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term of outstanding stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of share options (or share units) exercised during the current period.

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